Assessment of endometrial function during sustained delivery of estradiol and estradiol plus progesterone in ovariectomized rats

Abstract

Previous studies conducted in our laboratories have documented that tricalcium phosphate lysine (TCPL) delivery system can be utilized to deliver estrogen (E) and combination of estrogen with progesterone (E + P) at sustained levels for long duration in intact rats. The specific aim of this investigation was to attempt to reverse the endometrial changes resulted from post-ovariectomy by exogenously delivering sustained levels of E and E + P. A total of 27 adult female rats were used in this study. The animals were randomly divided into seven different groups: groups 1 animals served as intact control group, groups 2 and 6 animals were ovariectomized, 3 and 7 were ovariectomized (OVX) and implanted with TCPL loaded with E (20 mg loaded TCPL), and group 4 was OVX and implanted with E (TCPL, 20 mg) + P (TCPL, 40 mg.) treatment. Group 5 animals served, as intact control group. Blood samples were collected biweekly for 47 days. Vaginal smears were taken and screened daily during the entire investigation. Histopathological evaluations were conducted on reproductive as well as vital organs (H & E). Data obtained from this investigation suggest the following: (I) OVX resulted in an increase in total body weight, however E and E + P maintained the body weights at prior ovariectomy level, (II) sustained delivery of E resulted in maturation of vaginal epithelium and the smears exhibited the estrus at the end of 72 hours post implantation and continued this trend for the duration of the study, (III) E + P treatment induced no estrus and the epithelial changes resembled the OVX group, and (IV) E and E + P treatment resulted in a significant different (P < 0.05) in MDA levels compared to OVX and intact control groups. Results of this investigation conclude that sustained delivery of E and E + P by TCPL can be utilized to maintain the normal function of the reproductive organs and could serve as an efficient and safe therapy in estrogen deficient patients.